This invention relates generally to the field of bulk materials handling and more specifically to an apparatus for use with a flexible silo, stationary or mobile; or flexible bulk container filling apparatus; or flexible bulk container discharging apparatus.
Flexible Silos and Flexible Portable Bins
Silos, bins, hoppers, day bins and portable bins are presently known for use as rigid bulk storage containers for powder and granular product comprising a cone section with an outlet and using a wide variety of valves or flow control devices that can be used to control product flow. A vertical straight side section above the cone section increases the storage capacity. These storage systems are usually constructed with a storage container body made of steel, aluminum or plastic and have a support structure usually constructed of steel or aluminum and sometimes rigid plastic.
It is also known that product flow from such containers can be unreliable. Brute force equipment such as a mechanical agitator, pulsing cone valve or air injector devices can be installed inside the silo or bin cone near the outlet to facilitate product flow. A vibrator mounted on the silo wall can be used to assist product flow from a silo
Filling powder or granular product into rigid storage containers often results in blended products becoming unblended and fragile products can be damaged. This results from the free-fall and velocity of product descending from upstream equipment through the empty volume of the container and onto the bottom of the container. Air inside of the empty container mixes with the incoming product yet must be displaced and removed from the container as more product enters. Therefore, displaced air containing airborne product exits the container and is lost to the atmosphere or must be contained and separated using a dust collection system. Product that aerates while transferring into the flexible silo will be less dense resulting in inefficient use of the container volume.
Mobile portable bins that can be transported from one point for filling and to another point for discharging are also known.
Flexible silos fabricated of flexible fabric material for the silo body are a lower cost option to rigid steel or plastic silos and are used similarly in function as rigid storage bins.
The shape and function of the flexible silo and mobile portable flexible bin are designed to mimic the design and function of their rigid counterparts. Although flexible containers offer cost savings over other rigid materials, little to no provision is made take full advantage of the light weight and flexibility of the fabric container. Filling and discharging of product is quite similar for both rigid and flexible bulk containers
A flexible silo or bin can be easily collapsed and expanded both in width and in height. While means are sometimes employed to flex the side walls of the flexible container to assist product flow from the container during discharge, no provision is made to take advantage of the ability to reduce and expand the height of the container as a function to minimize free fall and velocity of product entering the container during filling. In addition, no provision is made to jog or pulse the container in a vertical or “Y” plane as a product flow enhancement method.
Further, when filling bulk product into a flexible silo or bin, the material forms a peak in the center of the pile as the product fills the container. As the peak reaches the top of the container, no more product can be added. This peak, known as the material's angle of repose, leads to inefficient use of the container storage volume. A void is created around the top area of the container around the upper perimeter where product cannot reach. Improvement in reducing or eliminating the empty void caused by the material angle of repose when filling a flexible bulk container is needed.
No provision is made to push the flexible silo bottom upward toward the inlet to expel most or all of the air. And, no provision is made to lower the bottom away from the inlet while dense, non-aerated product fills the container.
Improvement in reducing or eliminating the empty void caused by the material's angle of repose when filling a flexible bulk silo or bin is needed. To facilitate product flow from a flexible silo or bin, mechanical agitation means such those seen used on bulk bag discharging equipment can be employed. However, air injection type flow aids are more commonly used. Air injected into a container to facilitate product flow must be evacuated, thereby, resulting in additional pollution control equipment and loss of product. An alternative to injecting air into the container is to use two-ply fabric silo construction. The bottom or cone section of a flexible silo has two plies of fabric, an inner ply and an outer ply with an air gap in between. Air is injected into the space between the two plies to deform the inner ply and apply pressure to the product stored within the flexible silo and to change the shape of the interior ply wall. This approach requires airtight materials and seam construction and very heavy duty fabric. There is an associated increase in container cost. In addition, air line connections and power source connections preclude this design from practical use for mobile portable bins.
Utilizing the vertical flexibility of the flexible bulk container to enhance product flow is not considered in present method flexible silo and bin design. Improvement in utilizing the vertical flexibility of a flexible silo or bin for enhancing product flow from the container is needed.
Further still, although flexible mobile portable bin designs are presently utilized, improvement in providing product flow enhancing means and maintaining practical mobility and ease of use is needed.
Bulk Bag Filling
Bulk bags with lifting loops or sleeves attached to the upper perimeter of the bag can be used as replaceable, disposable storage containers. They require associated bulk bag filling and discharging equipment. Common practice involves filling a bulk bag at one location and transporting it for use and discharge at another location.
When filling bulk bags with bulk product, the material's angle of repose results in inefficient use of the container storage volume. In addition, bulk bags, after they are filled are often stacked two to three bags high. The peak of material interferes with stable stacking of the containers.
Three types of apparatus in which the base support table of a bulk bag filling apparatus can be raised and lowered to address this issue are disclosed in U.S. Pat. Nos. 4,718,464; 5,336,853 and 7,165,498. A described in the patents, a cone shaped table positioned within the base of the bulk bag filling apparatus is raised upward into the lower portion of a bulk bag by a lifting means which creates an indentation in the bag bottom. After the container is mostly filled with product, the lift table is lowered which relaxes the indentation in the bag bottom. The peak of the angle of repose of the product will also relax downward as the lift table lowers which results in a level surface of product in the container. At least one vibrator can be housed under the lift table to induce vibration into the product as a means to separate air from the product inside the bulk bag.
In carrying out the inventions, the filled bulk bag must remain suspended above the lift table because the cone shaped table is not broad enough and it does not provide a stable base to release the filled bulk bag onto. The suspended filled bulk bag must be removed by a fork lift having a pallet on the fork tines or by an automated platform that travels on rails into the space between the suspended bulk bag and the lowered cone lift table. Once one of these platforms is positioned under the bulk bag, the filled bulk bag can be released onto the platform and then removed from the bulk bag filling apparatus.
A simpler, more efficient means to reduce the peak formed by the angle of repose and a simpler, more efficient means to release a filled bulk bag onto a level platform is needed.
Bulk Bag Discharging
To discharge the bulk material stored within a bulk bag, the filled bulk bag is hoisted onto a bulk bag discharging apparatus. The apparatus provides loop or sleeve supports for suspending the bulk bag.
Bag squeezing devices mounted along the sides of the discharger frame are sometimes used to assist with product flow from the container. The most common flow assist apparatus utilizes at least two inclined panels, each positioned opposite the other. The panels provide a base for the product filled bag to rest upon and have a gap between the inner edges for the bag outlet spout to pass through. Each panel has a stationary pivot located at the inner base end with a piston and cylinder type actuator having one end pivot mount at a point along the panel and a second end pivot mount on the structure. When the actuators extend, the base mounts pivot and remain level as the outer ends of the panels arc inward thereby applying pressure against the bag. As product leaves the bag, the actuators move the upper ends of the panels further inward in an arc motion to increase the angle of the base of the bulk bag. The actuators can also be pulsed to provide agitation to the product to assist product flow.
It is also known that a flexible silo or bulk bag, when supported from the top, needs to be lifted as product discharges because the cube shaped flexible container narrows in width and elongates.
A hoist lift or other bag lifting mechanism can be used to support the loops or sleeves of the bulk bag which can be raised up incrementally as product leaves the container to compensate for elongation and to keep the lower portion of the bag and bag bottom walls as vertical as possible to allow product to exit the container.
Inclined panels having fixed base pivot mounts are an effective means of gradually increasing the angle of the sides of a bulk bag as product leaves the container. However, because the base of the flexible bulk bag remains level, in the case of no product flow, the actuators squeeze and compact the product stored in the container.
An improved means to change the angle the bulk bag base support members and to maintain tension on the flexible container as it elongates as product vacates the container is needed.
A means to enhance product flow from a filled bulk bag yet avoid squeezing the product stored within the container is needed.